1. Field of the Invention
The invention relates to a membrane or plug structure applied to the ostium of an atrial appendage for preventing blood flow and physical connection between an atrium of the heart and the associated atrial appendage or appendages to isolate an atrial appendage and prevent thrombus leaving therefrom.
2. Description of the Related Art
There are a number of heart diseases (e.g. coronary artery disease, mitral valve disease) that have various adverse effects on the heart. An adverse effect of certain cardiac diseases, such as mitral valve disease, is atrial (or auricular) fibrillation. Atrial fibrillation may result in pooling of blood in the left atrial appendage. Blood pooling may also be spontaneous. When blood pools in the atrial appendage, blood clots can form and accumulate therein, build upon themselves, and propagate out from the atrial appendage into the atrium. These blood clots can then enter the systemic or pulmonary circulations and cause serious problems if they migrate from the atrial appendage and become free in the blood stream and embolize distally into the arterial system. Similar problems also occur when a blood clot extending from an atrial appendage into an atrium breaks off and enters the blood supply. Since blood from the left atrium and ventricle supply the heart and brain, blood clots from the atrial appendages can obstruct blood flow therein causing heart attacks, strokes or other organ ischemia. It is therefore necessary to find a means of preventing blood clots from forming in the atrial appendages and to prevent these blood clots, once formed, from leaving the atrial appendages to the heart lungs, brain or other circulations of the patient which can cause heart attacks or strokes or other organ ischemia
U.S. Pat. No. 5,865,791 relates to the reduction of regions of blood stasis and ultimately thrombus formation in such regions, particularly in the atrial appendages of patients with atrial fibrillation. More specifically, the invention relates to procedures and devices for affixing the atrial appendages in an orientation that prevents subsequent formation of thrombus. The invention removes the appendage from the atrium by pulling on it and putting a loop around it to form a sack of the atrial appendage and then cut off from the rest of the heart.
U.S. Pat. No. 5,306,234 relates to a method for surgically closing the passage between the atrium and the atrial appendage or severing the atrial appendage.
Other methods of treatment include surgically removing the atrial appendages to prevent blood stasis in the atrial appendages.
The invention provides a membrane or plug structure for preventing blood from entering the atrial appendages to form blood clots and prevents blood clots formed in the atrial appendages from exiting therefrom which may cause heart attacks, strokes and other embolic events. The membrane covers the ostium of the atrial appendage and effectively isolates it from the atrium. It may be larger than the ostium of the appendage, and extend over an area larger than the appendage ostium. It is percutaneously delivered to the ostium of the atrial appendage by a catheter and then expanded to cover the ostium and has a means to attach the membrane over the ostium. The membrane itself may be porous or non-porous. In the case of a porous membrane, it can become infiltrated with cells so that it becomes a xe2x80x9clivingxe2x80x9d structure, and can develop an endothelial/endocardial lining to enable it in turn to become a non-thrombogenic surface. There are many means for fixing the membrane to cover the ostium of the atrial membrane. The membrane""s attachment devices have a means for self-centering the membrane over the appendage ostium. The membrane may be glued on, or have a stents or prongs which pass through the ostium and extend into or through the atrial appendage. Alternatively an anchor in the wall of the atrial appendage may be tethered to the membrane for holding the membrane in place. Springs may also extend between the anchor and the membrane to hold the membrane against the ostium. The membrane may also be connected to a tether, elastic tether or spring and placed through the atrial appendage wall for holding the membrane against the ostium and may pull on the atrial appendage such that its volume is reduced or eliminated, trapping and isolating blood clots therein. Thrombin, activated fibrinogen, or other biologic filler may be placed in the appendage after it has been sealed, with the express purpose of clotting the blood in the appendage, yet preventing clots from escaping the appendage.
Part of the device may involve a suction apparatus to remove clots that are already in place. The membrane placement may require closure of an atrial septal defect created by the placement of this appendage occluder device.
Alternatively the membrane may be held in place by a coiled spring filling the volume of the atrial appendage. The membrane may also fill the atrial appendage itself preventing blood from entering or blood clots from leaving.
The membrane itself may be porous or non-porous. In the case of a porous membrane, it can become infiltrated with cells so that it becomes a xe2x80x9clivingxe2x80x9d structure, and can develop an endothelial/endocardial lining to enable it in turn to become a nonthrombogenic surface. It thus can develop an endothelium and with time becomes highly biocompatible. It may be heparin-coated to prevent thrombus from forming on the membrane surface, immediately after placement and until it infiltrates with cells and/or develops an endothelial covering.
The device, when implanted in the atrial appendage, may also have the ability to perform electrical monitoring of the heart. This would consist of two or more electrical contacts placed apart on the device, and connected to signal conditioning circuitry for determination of cardiac features such as rhythm of the atria or ventricles. Another sensor on the device could measure pressure of the atria, atrial appendage, or ventricular end diastolic pressures (left or right) through the open mitral or tricuspid valves. A suitable telemetry system would be used to telemeter this important electrical and hemodynamic information non-invasively outside the patient. Also, memory could be present on the device in order to record the information for later recovery via noninvasive telemetry.
This device can also be used to close filstulae or connections elsewhere in the body, such as in the colon or bronchopulmonary systems. Another application of the device would be to seal and strengthen false aneuryms of the left ventricle by holding the membrane against the false aneurysm. The same principles apply, whereby the membrane is held against the fistulae or false aneurysm, held in place by the spring or prong mechanisms.
The device can also be used to chemically ablate the myocardial tissue of the atrial appendage in order to help limit or eliminate the electrical propagation of atrial fibrillation.
It is an object of the invention to reduce the volume of an atrial appendage to reduce the size of the region for potential blood stasis formation, and consequently the effective volume of the affected atrium.
It is an object of the invention to measure hemodynamics pressure (or flow), or electrical signals in the heart and telemeter them outside the body for diagnosis or monitoring.
It is an object of the invention to be able to close fistulae or connections elsewhere in the body, such as in the colon or bronchopulmonary systems.
It is another object of the invention for the membrane to be placed in a false aneurysm to strengthen this defect, and to avoid surgery.
It is an object of the invention to reduce the region of static blood in the atrial appendages and hence the thrombogenicity of the atrium.
It is an object of the invention to prevent blood clots from forming in the atrial appendages.
It is an object of the invention to replace the ostium of the atrial appendage with a non-thrombogenic, biocompatible surface that prevents blood clots from forming.
It is an object of the invention to provide a porous membrane surface which becomes lined with endothelial or endocardial cells.
It is an object of the invention to isolate the atrial appendage from the atrium proper and prevent communication through which thrombus could migrate.
It is an object of the invention to minimally invasively prevent blood clots from forming in the atrial appendages and escaping therefrom.
It is an object of the invention to provide a filter between the atrium and atrial appendage to prevent blood clots from flowing therebetween.
It is an object of the invention to fill the atrial appendage with a material to prevent blood clots from leaving the atrial appendage.
It is an object of the invention to remove thrombi from the atrium via suction or other means.
It is an object of the invention to provide a means for securing a membrane over the ostium of the atrial appendage that is colonized with cells and provide a highly biocompatible surface including but not limited to endothelialization.
It is an object of the invention to prevent thrombus by use of heparin or other anti-thrombogenic substance on or eluted from the membrane.
It is an object of the invention to seal the membrane with a substance injected into the atrial appendage.
It is an object of the invention to clot the blood inside of the atrial appendage after the membrane is in place with a substance injected into the atrial appendage.
It is an object of the invention to inject a substance into the sealed appendage to ablate the myocardial cells of the appendage, in order to limit the propagation of atrial fibrillation.
It is an object of the invention to ensure the membrane is centered over the ostium of the atrial appendage.
It is an object of the invention to accurately place the membrane over the ostium of the atrial appendage.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.